1. Field
The disclosed embodiments generally relate to fastener systems including fastener, driver, method of manufacture and related tooling. In particular to fasteners having spiral drive and removal surfaces that enable high seating torques to be applied.
2. Brief Description of Related Developments
Fasteners having driver engageable surfaces that are, at least in part, defined by spiral segments have been used with good results. Fastener systems of this type are described in U.S. Pat. Nos. 5,957,645, 6,234,914, and 6,367,358 issued to Stacy and commonly owned with this application. The disclosures of these patents are incorporated herein by reference. The drive surfaces of the Stacy fastener system are constructed to maximize torque transmission, during installation and removal, while spreading the driving load over a broad driver/fastener interface. The thrust of these teachings is to enlarge the area of the drive surfaces.
More recently certain applications have been found that require the application of high seating torques to the fastener. Such torques may exceed the strength limits of the drivers used to seat the fastener. It is the purpose of this invention to provide an improved driver/fastener interface to increase the available seating torque characteristic of the fastener system.
The problem to which this application is directed, therefore, is to construct a drive fastener interface that increases the strength of the driver without significantly effecting the load distribution characteristics of the spiral interface surfaces.